That is a good question that i need to be asking myself. I guess i would be o.k. spending the money to adequately light the 4 x 4. I will be using an assortment of timber grow lights; daisies and fixtures for both veg and flowering. i have read that 4x4's are roughly good for flowering 4-6 plants and 3x3's are good for roughly fowering 3-4 plants. I am guessing this is influenced by hydro set-up, skill, strain, and experience as well. This is kind of what I am trying to process. I don't want to get too big of a tent, but not too small of a tent either. Both seem to be a good sizes. I guess, if I can harvest enough from a 3x3 to meet my needs, that would not be bad either. Any info to help process would be great, friend. Please and thanks.